The present invention relates to a position detection surveying device for detecting a position of a target, and more particularly to a position detection surveying device which is most suitable for an automatic surveying apparatus and, without using expensive acoustooptic devices, can be miniaturized and manufactured so that it saves the electric power.
An automatic surveying apparatus, which enables a position of a target to be detected, has been recently developed, and a one-man operated surveying is now being employed widely. This automatic surveying apparatus comprises units such as a scanning unit, a range measuring unit, and an angle measuring unit, and was constituted by means such as a driving means for rotating the main body in a horizontal direction and a driving means for rotating a mirror cylinder in a vertical direction.
A detection for a prism set on a target is performed using a reflected light of a light launched out from the scanning unit toward the target. The constitution of the detecting process is as follows: The reflected and received light is converted into a light reception signal at a light receiving unit. The light reception signal is feedback-controlled into rotating means or the driving means, thereby causing the automatic surveying apparatus to turn toward a direction of the target.
A laser light launched out from the scanning unit is deflected in both a horizontal and a vertical direction by acoustooptic devices. The state of the laser light thus deflected resembles that of a laser light whose specified part in the launched direction has been, for example, Lissajous-scanned.
Based on FIG. 15, the description will be given below in connection with deflecting means using the acoustooptic devices:
A laser diode 21 emits an infrared laser light as a scanning light, and a collimator lens converts the infrared laser light into a parallel pencil of rays. Both a horizontal deflecting device 23 and a vertical deflecting device 24 are acoustooptic devices in this case. The horizontal deflecting device 23 and the vertical deflecting device 24 deflect the infrared laser light in a horizontal direction H and in a vertical direction V, respectively. However, the deflecting means employing the above-mentioned acoustooptic devices are very expensive, causing an increase in the production cost. In addition to this, the deflecting means are accompanied by a heat generation, thus increasing the power consumption. These resulted in a problem that, practically, it becomes difficult to drive them using small-sized batteries.
Accordingly, there was need of carrying a line power supply or a large-sized battery pack, which led to serious problems of causing a reduction in portability as well as a decrease in the operation efficiency in surveying.
Furthermore, the acoustooptic devices have a limited deflection angle. This resulted in another problem that, in order to enlarge scanning extent, there is need of rotating the mirror cylinder in a vertical direction.